Does it though?

A good spec really only needs clear principles. At a minimum, it should clearly explain what it does do, and also clearly explain what it does not do.

You don't need to have every edge case covered to build an API for datagrids. iOS has had native DataGrids for ages, Windows, macOS, Android. They all have this stuff built in. Other platforms have figured out how to provide these API surfaces.

Why does the web have to be seen as a special unicorn that can't have good baseline components like these platforms?

Are any of the examples you gave an open standard with multiple implementations from different companies? If Apple gets their implementation wrong, they can always deprecate an API and move forward. If they want to throw out an old implementation and deprecate that completely and start over, they can do that. The Web standard depends on agreement by multiple large organizations. That level of communication slows everything down. If they get an API wrong, we’re stuck with it forever.

That’s why the web is a special unicorn. It’s very different than those platforms. Web standards should be small and composable. They shouldn’t try to solve every problem. I get why you would want a data grid. Maybe in your work it’s a common pattern. But on the broader web and in all of the documents that are out there, it’s on a minute fraction of them. It’s simply not worth the effort. Too much effort, too little gain.